HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 09:00 ON SATURDAY APR 16TH 2016
THE CURRENT GENERAL SITUATION A ridge of High pressure is building across Southern Britain today. Weak troughs of Low pressure will move East over the far North later today and more slowly SE across other areas tonight and tomorrow weakening further as they run into High pressure over Southern England by then.
http://www.wetterzentrale.de/pics/Rtavn001.gif
CURRENT SNOW FORECAST AND FREEZING LEVEL OVER THE UK The frezing level across the UK currently is around 2000ft but it will rise to around 3500ft for many by tomorrow and much higher across the South around midweek, perhaps to as high as 10000ft by midweek as warmer air moves up from the South. As a result snowfall will be impossible on lowland Britain later this week.
http://www.snow-forecast.com/maps/dynamic/uk
http://www.natice.noaa.gov/pub/ims/ims_gif/DATA/cursnow.gif
MODELS-2 WEEK HEADLINE A lot of dry and bright weather this week with cool nights then even chillier weather with sunshine and showers look likely with a continuing night frost risk thereafter.
THE GFS JET STREAM FORECAST The split flow in the Jet Stream will remain with the main arm well South over the area of Southern Spain and North Africa with low pressure West of Portugal. The northern arm while weak moves East near Northern Scotland and this buckles at times later this week as the Southern arm also sends a spore North to the UK before the flow simplifies to a single flow blowing North to South over the UK and sets up a cyclonic airstream near the UK at the end of the period.
http://www.netweather.tv/index.cgi?action=jetstream
GFS OPERATIONAL The GFS Operational Run today shows a lot of High pressure influenced weather across the UK although the positioning of this is poor for the UK. Through the working week High pressure well establishes across the UK with fine weather developing for all but with cool nights and some frost the days will be bright and sunny. Later in the week a SE flow across the far South and SW could give rise to some potentially thundery rain before winds back NE for all and temperatures decline once more next weekend with the second week looking very cool and showery with some wintry showers over hills and frost at night even more likely under winds from such a cold source to the North. The best weather then looks to be towards the NW before all areas look like warming up a little at the very end of the period as winds finally return to a milder Westerly source.
GFS CONTROL RUN Apart from minor details the Control Run offers only small differences and that occurring in the much more unreliable part of the run in the second week. As it is things get much more complex in Week 2 as Low pressure is shown to elongate the UK with cold air to the North and warmer air pushing up into the South. This means rain at times for many but possibly becoming warmer and more Spring feeling in the South with time.
http://www.wetterzentrale.de/pics/Rtavn1441.gif
http://www.wetterzentrale.de/pics/Rtavn3841.gif
http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=144&mode=0&carte=0
http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=384&mode=0&carte=0
GFS ENSEMBLE DAY 14 DATA The GFS Clusters today are all over the place again with no clear pattern determined by this morning's set. As they stand there is around equal support for some sort of cold Northerly flow over the UK with low pressure to the East and High to the West whereas there is another equally big group who support the opposite of High pressure to the East and Low pressure over or just to the West of the UK with South or SW winds and undoubtedly less cool conditions as a result. Not a lot can be drawn from this pack this morning.
http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=372&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=
UKMO The UKMO model this morning shows High pressure well in control over much of this working week although some sort of hiatus could develop across the extreme South midweek as Low pressure to the South brings the risk of some showery rain here for a time. then as we look towards next weekend UKM looks to be setting itself up for the UK to have another very cool weekend of sunshine and showers with frosts at night under a strengthening NE or North flow.
http://www.wetterzentrale.de/pics/Rukm1441.gif
THE FAX CHARTS The Fax Charts show High pressure developing across the South of Britain over the coming days and killing off a weak front moving down from the North by Tuesday. Then High pressure builds across all areas for a time before a pincer movement develops caused by troughs from both the North and South moving towards one another by the end of the week.
http://www.weathercharts.org/ukmomslp.htm#t120
GEM GEM this morning is a little slower in bringing the cold North or NE flow into the UK, leaving it until after next weekend before the main thrust of rain and cold showers feeds down over us close to Low pressure near the SE to end the run. This leaves much of the coming week dry and bright with High pressure over or eventually just to the West and NW with a ridge close by though this model too runs a risk of showery rain over the extreme South soon after midweek as things warm up for a time.
http://www.wetterzentrale.de/pics/Rgem2401.gif
NAVGEM NAVGEM too shows good support for a High pressure based week to come with fine days with some sunshine mixed with chilly nights with frost in places. Some exceptions to this theme also look possible with the same risk of showery rain in the far South soon after midweek this coupled with falling pressure later culminates in High pressure being sucked back out into the Atlantic late in the week and next weekend at the expense of a cold Northerly flow establishing with showers and cold winds to end the period.
http://www.wetterzentrale.de/pics/Rnvg1681.gif
ECM ECM today still maintains the theme it has for days now of a High pressure based week to come as it builds across Southern Britain over the next 24 hours or so before extending North to all areas by midweek. A freshening Easterly will then develop across the South and with fronts over the channel some showery rain could develop here soon after midweek. Then as for some considerable while now the model has all eyes looking to the North and NE as showery Low pressure pulls down a cold Northerly airflow as result of High pressure being sucked out over the Atlantic and Greenland to end the period. This could spell quite a protracted period of cool and perhaps very unsettled weather for much of the UK given such extensive High pressure blocking to the North and NW is shown at Day 10.
http://www.wetterzentrale.de/pics/Recm2401.gif
ECM 10 DAY MEAN (12z) The 240hr mean Chart from last night endorses the Operational Run issued this morning well with a cold Northerly flow with sunshine and showers a strong theme offered to the UK this morning for 10 days time.
http://www.wetterzentrale.de/pics/Reem2401.gif
NOTABLE TRENDS & CHANGES FROM PREVIOUS RUNS Still too much emphasis on the trend for cool and showery North or NE winds to be blowing down across the UK in 10-14 days time for my liking. However, that again is the main theme this morning.
31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The verification Statistics of GFS, UKMO and ECM show at 24 hours ECM ahead at 99.6 pts with UKMO at 99.5 pts and GFS at 99.3 pts. At 3 days ECM is leading with 97.4 pts to UKMO's 96.8 pts while GFS lags behind at 95.6 pts. At 5 days ECM leads with 89.7 pts to UKMO at 87.5 pts and GFS at 84.0 pts. Then at 8 Days ECM has the leading spot from GFS with 65.6 pts to 59.8 pts. Finally at Day 10 ECM has the lead from GFS with a score of 44.0 pts to 39.4 pts.
http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day1_PMSL_MSL_G2NHX.png
http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day3_PMSL_MSL_G2NHX.png
http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_PMSL_MSL_G2NHX.png
http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day8_PMSL_MSL_G2NHX.png
http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day10_PMSL_MSL_G2NHX.png
MY THOUGHTS Another day and no change in the models theme this morning and with a lot of cross model support the theme of weather I'm about to describe for the next few weeks comes with a higher degree of certainty than is often the case. What we currently have is pressure rising across the UK as a strong ridge develops over Southern England in the coming day or so. For a time a weak Westerly flow will permit weak troughs to bring cloud and a little rain across the UK and this may approach the South too tomorrow before the front responsible dies in situ as the High pressure develops and extends North. This then leads to much of the UK having a largely dry and settled three or four days with some chilly night but bright and warm sunshine by day. Low pressure will be flirting with Southern England from midweek and this could lead to some showery rain extending North from France on Thursday under a previously strengthening ESE flow while in the North it stays dry and fine until the weekend. Thereafter things get much more complicated although the message from all the models is an assured one. High pressure will be retrogressing to the West and NW at the weekend and coupled with Low pressure to the SE and later East and NE cold north winds are expected to flood back down across the UK next weekend and then last for some considerable time. Although day to day details between the models are shown I can generalise by saying that this period looks like being rather cold and showery and the air still looks cold enough for some snow in the showers over the hills with hail, graupel and thunder possible almost anywhere between spells of sparkling sunshine and good visiblities. More importantly for gardeners and growers frost by night look inevitable on occasions as showers and clouds decay away each evening. Then if I have to look at the crystal ball for the days between Day 10-14 I think we can say that winds may back Westerly with time allowing somewhat less cold though still changeable conditions to develop as we move into May proper. So there you have it a lot of dry and fine weather over the week to come looks like being superseded by another cold attack from the North or NE next weekend with the lead up to the Bank Holiday Weekend at the turn of the month looking a cool and showery one although as always in showery setups some fair better than others and overall with no persistent rain or gales looking likely away from the cold showers and night frosts things overall may not feel too bad.
Next Update Monday April 18th 2016 from 09:00
Martin G
Kilmersdon Radstock Bath Somerset